Dedent system

ABSTRACT

The invention provides a dedent system, which comprises a bullet shank and a cable shank. The bullet shank comprises a male shank portion and a first latching portion. The first latching portion comprises a first contacting surface and a locking hole, and the locking hole is tilted such that an opening on the first contacting surface is closer to the male shank portion than a portion of the locking hole which is farther from the first contacting surface. The cable shank comprises a female shank portion and a second latching portion. The second latching portion comprises a second contacting surface and a locking bump. The female shank is connected to a cable, and the locking bump is tilted such that a portion of the locking bump on the first contacting surface is farther to the female shank portion than the a tip portion of the locking bump.

RELATED APPLICATION

This application is a continuation-in-part of U.S. patent application Ser. Nos. 11/308,453 for “Method for Repairing Metal Pipe” filed on Mar. 27, 2006.

BACKGROUND OF THE INVENTION

The present invention relates to a dedent system for repairing metal pipe.

More particularly, this invention relates to a dedent system using bullet and cable shanks for repairing metal pipe damaged with dents.

Prior to the present invention, all pipe sizes 3″, and under that were damaged were scrapped.

Metal pipes of 4″ and larger were repaired by using a jack system that was very labor intensive. Actually, there are very few repair services available in the pipe industry. The lead time of the major steel service centers to get material repaired was in excess of 4-6 months. During all those long time period the damaged pipe would sit out in the yard rusting to the point that it was no longer considered prime material. This is another reason why many companies would opt to reject in full damaged material.

On all pipe received at the harbor 30% damage is minimum for schedule 10 wall thickness. Lighter walls have in excess of 40% damage.

Insurance companies typically will not insure a product that consistently has more that 10 to 20% damage rate.

Using the present invention, 99% of all damaged material (1¼″ to 6″ nominal) is now able to be repaired in the schedule 10 and under wall thicknesses.

Thousands of feet of pipe can be straightened and have dents removed daily.

Lower insurance premiums will be realized as fewer claims are registered.

Repair cost of 4″ and 6″ pipe are reduced greatly.

1¼″ to 3″ are now repaired and returned to stock and sold as new material.

U.S. patent application Ser. No. 11/308,453 by the applicant discloses a method and system for repairing metal pipes.

Accordingly, a need for a method for repairing metal pipe has been present for a long time considering the range of pipe use in the modern industrial society. This invention is directed to solve the problems and satisfy the long-felt need.

SUMMARY OF THE INVENTION

The present invention contrives to solve the disadvantages of the prior art.

An object of the invention is to provide a dedent system for repairing a damaged pipe.

Another object of the invention is to provide a dedent system using bullet and cable shanks for repairing a damaged pipe, which can push out the dents and remove the damage from the pipe.

An aspect of the invention provides a dedent system for repairing a pipe damaged with dents, which comprises a bullet shank and a cable shank.

The bullet shank comprises a male shank portion and a first latching portion. The first latching portion comprises a first contacting surface and a locking hole provided through the first contacting surface and the male shank portion is configured to be connected with a mandrel, and the locking hole is tilted such that an opening on the first contacting surface is closer to the male shank portion than a portion of the locking hole which is farther from the first contacting surface.

The cable shank comprises a female shank portion and a second latching portion. The second latching portion comprises a second contacting surface and a locking bump provided on the second contacting surface, and the locking bump is configured to engage with the locking hole of the bullet shank. The female shank is configured to be connected to a cable, and the locking bump is tilted such that a portion of the locking bump on the first contacting surface is farther to the female shank portion than the a tip portion of the locking bump.

The bullet shank and the cable shank are connected by engaging the locking hole and bump so as to be engaged under a force in a first direction parallel to the axis of the cylinders and easily disengaged from each other under a force in a second direction perpendicular to the axis of the cylinders.

The male shank portion of the bullet shank may have a shape of cylinder, and the first latching portion of the bullet shank may have a shape of half-cylinder sharing an axis with the male shank portion.

The first contacting surface of the latching portion of the bullet shank may be substantially flat and parallel to the axis of the cylinders. The locking hole of the bullet shank may be substantially perpendicular to the axis of the cylinders, and a cross-section of the locking hole may be oblong.

The female shank portion of the cable shank may have a shape of cylindrical tube. The second latching portion of the cable shank may have a shape of half-cylinder sharing an axis with the cable shank portion, and the second contacting surface of the second latching portion of the cable shank may be substantially flat and parallel to the axis of the cylinders.

The locking bump of the cable shank may extend substantially perpendicularly to the axis of the cylinders. The locking bump of the cable shank may be configured to lock with the locking hole of the bullet shank, and the first and second contacting surfaces may contact each other across most of the first and second contacting surfaces.

The dedent system may further comprise a pipe holding device, the mandrel, the cable, a winch, and a slope.

The pipe holding device for holding the pipe having a near end and a far end in position may comprise a processing deck for supporting the pipe in position, an overhanging deck for holding and positioning the pipe, and a pipe stopper for aligning and stopping the pipe against the force exerted by the mandrel driven by the winch.

The mandrel, with a cross section and size adapted to be pulled through the interior of the pipe from the far end to the near end, may have a first edge, a second edge, and a side surface.

The cable may have first and second ends, and the first end may be queued into the pipe and detachably attached to the first edge of the mandrel at the far end of the pipe.

The winch may be disposed at the near end of the pipe and connected to the second end of the cable for winding up the cable.

The slope is disposed by the cable and tilted from the far end of the pipe to the near end of the pipe.

The mandrel may be pulled by the winch with the cable. The mandrel may travel through the pipe to push out from inside and remove the dents on the surface of the pipe. The slope may be configured to return the mandrel from the far end to the near end.

A method for repairing metal pipe with dents includes steps of a) holding the pipe with first and second ends in position; b) dragging the mandrel through the pipe; and c) pushing out the dents from inside to an original level of the surface of the pipe.

The cross-section of the mandrel has a substantially same cross-section of the hollow space of a undamaged pipe, and the outer surface of the major portion of the mandrel fits tightly to the inside of the undamaged pipe.

The step of holding the pipe includes steps of a) guiding the pipe into a locking position along the direction of the axis of the pipe; b) stopping the pipe along the direction of the axis of the pipe against pressure imparted by momentum transfer from the friction between the pipe and the mandrel; and c) stopping the pipe along the perpendicular direction of the axis of the pipe against pressure imparted by momentum transfer from the friction between the pipe and the mandrel.

The step of guiding the pipe includes a step of using a bevel surface.

The step of stopping the pipe along the direction of the axis of the pipe includes a step of using a stopping surface connected to the bevel surface.

The step of stopping the pipe along the perpendicular direction of the axis of the pipe includes a step of using a plurality of V-shaped pipe rests and a plurality of hydraulic rams.

The step of dragging the mandrel through the pipe includes a step of pulling the mandrel using a winch connected to the mandrel with a cable.

The step of dragging the mandrel through the pipe includes a step of pushing the mandrel with a pushing rod.

The step of dragging the mandrel through the pipe includes a step of lubricating the contacting surface between the pipe and the mandrel.

The method may further include steps of a) connecting the mandrel to the cable before the step of dragging the mandrel through the pipe; b) putting a mandrel into the first end of the pipe before the step of dragging the mandrel through the pipe; c) pulling out the mandrel from the inside of the pipe at the second end after the step of pushing out the dents from inside; and d) disconnecting the mandrel from the cable after the step of pushing out the dents from inside.

The method may further include a step of delivering the mandrel from the second end of the pipe to the first end of the pipe.

The step of delivering the mandrel includes a step of using a slope, and the slope tilts from the second end to the first end.

The method may further include a step of using a system for repairing a pipe damaged with dents, which includes a pipe holding device, a mandrel, a cable, and a winch.

The pipe holding device is for holding the pipe in position.

The mandrel, with a cross section and size adapted to be pulled through the interior of the pipe, has a first edge, a second edge, and a side surface.

The cable has first and second ends, and the first end is detachably attached to the first edge of the mandrel.

The winch is connected to the second end of the cable for winding up the cable.

The mandrel is pulled by the winch with the cable and travels through the pipe to push out from inside and remove the dents on the surface of the pipe.

The pipe holding device includes a processing deck, an overhanging deck, and a pipe stopper.

The processing deck, for supporting the pipe in position, includes a lower beam with first and second ends and a plurality of pipe rests provided on the lower beam.

The overhanging deck, for holding and positioning the pipe, includes an upper beam and a plurality of hydraulic rams extending down from the upper beam.

The pipe stopper is for aligning and stopping the pipe against the force exerted by the mandrel driven by the winch.

The lower beam of the processing deck and the upper beam of the overhanging deck are made of a fabricated I beam. The dimension of the I beam is determined by the dimension of the damaged pipe. The I beam is approximately thirty five (35) feet long, approximately twelve (12) inches wide, and approximately seven (7) inches high.

The pipe rest of the processing deck is substantially V shaped.

The hydraulic ram comprises an arm extending from the upper beam and a pinning hand provided at the end of the arm. The pinning hand is substantially V-shaped.

The pipe stopper includes a bevel surface and a stopping surface, and the bevel surface and the stopping surface are adapted to align and stop the edge of the pipe. The bevel surface and the stopping surface meet each other in approximately from one hundred thirty five (135) to one hundred forty five (145) degrees.

The mandrel includes a tapered head part, a barrel part, and a mechanical fastener.

The tapered head part provided at the first edge, and the diameter is smoothly increasing.

The barrel part, with a diameter accommodating the inner diameter of the pipe, is connected to the tapered head part, provided on the side surface.

The mechanical fastener, for detachably attaching the cable, is provided at the end of the tapered head part.

The mechanical fastener includes a female screw thread.

Alternatively, the mechanical fastener includes a hooking device, in which case the cable includes a looping device adapted to the hooking device.

The winch includes a hydraulic pump. The hydraulic pump is driven by an electrical motor. The hydraulic pump may sense the pressure from the load, and the operation of the electrical motor is controlled by the sensed pressure accordingly.

The system for repairing pipe may further include a feeding rack, a discharge rack, and a slope.

The feeding rack is for feeding the pipes one by one to the processing deck. The discharge rack is for discharging the processed pipes out of the processing deck. The slope, for returning the mandrel, is tilted downward from the finishing end to the starting end.

The system for repairing pipe may further include a lubricant for reducing the friction and wear between the inner surface of the pipe and the side surface of the barrel part of the mandrel.

The advantages of the present invention are: (1) the system for repairing metal pipe makes it possible to repair metal pipe damaged with dents easily; and (2) the bullet and cable shanks make it easy and fast to connect and disconnect a mandrel in the dedent system.

Although the present invention is briefly summarized, the fuller understanding of the invention can be obtained by the following drawings, detailed description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention will become better understood with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a system for dedenting metal pipe according to the invention;

FIG. 2 is a partial blow-up view of FIG. 1;

FIG. 3 is a perspective view of a bullet shank according to an embodiment of the invention;

FIG. 4 is a side plan view of FIG. 3;

FIG. 5 is a top plan view of FIG. 3;

FIG. 6 is a front plan view of FIG. 3;

FIG. 7 is a rear plan view of FIG. 3;

FIG. 8 is a cross-section view along lines VIII-VIII of FIG. 7;

FIG. 9 is a perspective view of a cable shank according to an embodiment of the invention;

FIG. 10 is a side plan view of FIG. 9;

FIG. 11 is a top plan view of FIG. 9;

FIG. 12 is a front plan view of FIG. 9;

FIG. 13 is a rear plan view of FIG. 9;

FIG. 14 is a cross-section view along lines XIV-XIV of FIG. 13;

FIG. 15 is a perspective view of a system for repairing metal pipe according to the present invention;

FIG. 16 is a side plan view of an embodiment of a mandrel according to the present invention;

FIG. 17 is a schematic view showing the relations between a damaged pipe, a mandrel, a cable, and a winch;

FIG. 18 is a cross-sectional view of a pipe rest;

FIG. 19 is a front plan view of a pipe holding device;

FIG. 20 is a front plan view of a pipe stopper;

FIG. 21 is a cross-sectional view of the pipe stopper along the line X-X of FIG. 20;

FIG. 22 is a side plan view of another embodiment of a mandrel;

FIG. 23 shows a first end of a cable corresponding mandrel of FIG. 22;

FIG. 24 is a front view of a system according to the present invention with a feeding rack and a discharge rack; and

FIG. 25 is a side view of a system with a slope for returning the mandrel.

DETAILED DESCRIPTION OF THE INVENTION

The U.S. patent application Ser. No. 11/308,453 by the applicant is incorporated by reference into this disclosure as if fully set forth herein.

FIGS. 1 and 2 show a dedent system according to embodiments of the invention.

An aspect of the invention provides a dedent system 100 for repairing a pipe damaged with dents, which comprises a bullet shank 500 and a cable shank 600.

FIGS. 3-14 show the bullet shank 500 and the cable shank 600.

The bullet shank 500 comprises a male shank portion 510 and a first latching portion 520 as shown in FIGS. 4-8. The first latching portion 520 comprises a first contacting surface 522 and a locking hole 524 provided through the first contacting surface 522 and the male shank portion 510 is configured to be connected with a mandrel 20, and the locking hole 524 is tilted such that an opening 525 on the first contacting surface 522 is closer to the male shank portion 510 than a portion 526 of the locking hole 524 which is farther from the first contacting surface 522 as clearly seen in FIGS. 5 and 8. Therefore, the bullet shank 500 and the cable shank 600 are locked to each other while the mandrel 20 is pulled through the pipe.

The cable shank 600 comprises a female shank portion 610 and a second latching portion 620 as shown in FIGS. 10-14. The second latching portion 620 comprises a second contacting surface 622 and a locking bump 624 provided on the second contacting surface 622, and the locking bump 624 is configured to engage with the locking hole 524 of the bullet shank 500. The female shank 610 is configured to be connected to a cable 30, and the locking bump 624 is tilted such that a portion 625 of the locking bump 624 on the first contacting surface 622 is farther to the female shank portion 610 than the a tip portion 626 of the locking bump 624 as clearly seen in FIGS. 10, 11, and 14. The locking bump 624 may be tilted by an angle α, which may be from about 5 degrees to about 15 degrees. In the illustrated embodiment, the angle may be about 10 degrees.

The bullet shank 500 and the cable shank 600 are connected by engaging the locking hole 524 and the locking bump 624 so as to be engaged under a force in a first direction parallel to the axis of the cylinders and easily disengaged from each other under a force in a second direction perpendicular to the axis of the cylinders.

The male shank portion 510 of the bullet shank 500 may have a shape of cylinder, and the first latching portion 520 of the bullet shank 500 may have a shape of half-cylinder sharing an axis with the male shank portion 510.

The first contacting surface 522 of the latching portion 520 of the bullet shank 500 may be substantially flat and parallel to the axis of the cylinders. The locking hole 524 of the bullet shank 500 may be substantially perpendicular to the axis of the cylinders, and a cross-section of the locking hole 524 may be oblong as shown in the illustrated embodiments. The cross-section of the locking hole 524 may be oblong in general.

The female shank portion 610 of the cable shank 600 may have a shape of cylindrical tube as shown in FIGS. 9 and 14. The female shank portion 610 is configured to connect to the cable 30, and the cable 30 may be fixed into the hollow cylindrical tube. The second latching portion 620 of the cable shank 600 may have a shape of half-cylinder sharing an axis with the female shank portion 610, and the second contacting surface 622 of the second latching portion 620 of the cable shank 600 may be substantially flat and parallel to the axis of the cylinders.

The locking bump 624 of the cable shank 600 may extend substantially perpendicularly to the axis of the cylinders.

The locking bump 624 of the cable shank 600 may be configured to lock with or into the locking hole 524 of the bullet shank 500, and the first and second contacting surfaces 522, 622 may contact each other across most of the first and second contacting surfaces 522, 622.

The male shank portion 510 of the bullet shank 500 may have a thread around the outer surface of the cylinder for the mechanical fastener 25 as show in FIG. 16.

The dedent system 100 may further comprise a pipe holding device 10, the mandrel 20, the cable 30, a winch 40, and a slope 70 as shown in FIGS. 1, 2, and 15-25.

The pipe holding device 10 for holding the pipe having a near end and a far end in position may comprise a processing deck for supporting the pipe in position, an overhanging deck for holding and positioning the pipe, and a pipe stopper for aligning and stopping the pipe against the force exerted by the mandrel driven by the winch.

The mandrel 20, with a cross section and size adapted to be pulled through the interior of the pipe from the far end to the near end, may have a first edge, a second edge, and a side surface.

The cable 30 may have first and second ends, and the first end may be queued into the pipe and detachably attached to the first edge of the mandrel at the far end of the pipe.

The winch 40 may be disposed at the near end of the pipe and connected to the second end of the cable for winding up the cable.

The slope 70 is disposed by the cable and tilted from the far end of the pipe to the near end of the pipe.

The mandrel 20 may be pulled by the winch 40 with the cable 30. The mandrel 20 may travel through the pipe to push out from inside and remove the dents on the surface of the pipe. The slope may be configured to return the mandrel from the far end to the near end.

FIGS. 15 through 25 show a dedent system for a method of repairing metal pipe.

The method for repairing metal pipe 90 with dents 91 includes steps of a) holding the pipe 90 with first and second ends 92, 94 in position; b) dragging the mandrel 20 through the pipe 90; and c) pushing out the dents 91 from inside to an original level of the surface of the pipe 90.

The cross-section of the mandrel 20 has a substantially same cross-section of the hollow space of a undamaged pipe 90, and the outer surface of the major portion of the mandrel 20 fits tightly to the inside of the undamaged pipe 90.

The step of holding the pipe includes steps of a) guiding the pipe 90 into a locking position along the direction of the axis of the pipe 90; b) stopping the pipe 90 along the direction of the axis of the pipe 90 against pressure imparted by momentum transfer from the friction between the pipe 90 and the mandrel 20; and c) stopping the pipe 90 along the perpendicular direction of the axis of the pipe 90 against pressure imparted by momentum transfer from the friction between the pipe 90 and the mandrel 20.

The step of guiding the pipe 90 includes a step of using a bevel surface 162 as shown in FIG. 20.

The step of stopping the pipe 90 along the direction of the axis of the pipe 90 includes a step of using a stopping surface 164 connected to the bevel surface 162.

The step of stopping the pipe 90 along the perpendicular direction of the axis of the pipe 90 includes a step of using a plurality of V-shaped pipe rests 126 and a plurality of hydraulic rams 152 as shown in FIG. 18 and FIG. 19.

The step of dragging the mandrel 20 through the pipe 90 includes a step of pulling the mandrel 20 using a winch 40 connected to the mandrel 20 with a cable 30.

The step of dragging the mandrel 20 through the pipe 90 includes a step of pushing the mandrel 20 with a pushing rod (not shown).

The step of dragging the mandrel 20 through the pipe 90 includes a step of lubricating the contacting surface between the pipe 90 and the mandrel 20.

The method may further include steps of a) connecting the mandrel 20 to the cable 30 before the step of dragging the mandrel through the pipe 90; b) putting a mandrel 20 into the first end of the pipe 90 before the step of dragging the mandrel 20 through the pipe 90; c) pulling out the mandrel 20 from the inside of the pipe 90 at the second end after the step of pushing out the dents 91 from inside; and d) disconnecting the mandrel 20 from the cable 30 after the step of pushing out the dents 91 from inside.

The method may further include a step of delivering the mandrel 20 from the second end of the pipe 90 to the first end of the pipe 90.

The step of delivering the mandrel 20 includes a step of using a slope 70, and the slope 70 tilts from the second end 94 to the first end 92.

The method may further include a step of using a system 100 for repairing a pipe 90 damaged with dents 91, which includes a pipe holding device 10, a mandrel 20, a cable 30, and a winch 40 as shown in FIGS. 15 through 25.

FIG. 15 shows a perspective view of a system 100 for repairing metal pipe 90 according to the present invention

The system 100 for repairing a pipe damaged with dents 91 (refer to FIG. 17) includes a pipe holding device 10, a mandrel 20, a cable 30, and a winch 40.

The pipe holding device 10 is for holding the pipe 90 in position.

The mandrel 20, with a cross section and size adapted to be pulled through the interior of the pipe 90, has a first edge 22, a second edge 24, and a side surface 26 as shown in FIG. 16.

The cable 30 has first and second ends 32, 34, and the first end 32 is detachably attached to the first edge 22 of the mandrel 20 as shown in FIG. 17.

The winch 40 is connected to the second end 34 of the cable for winding up the cable 30 as shown in FIG. 17.

The mandrel 20 is pulled by the winch 40 with the cable 30 and travels through the pipe 90 to push out from inside and remove the dents 91 on the surface of the pipe 90 as shown in FIG. 17.

The pipe holding device 10 includes a processing deck 12, an overhanging deck 14, and a pipe stopper 16 as shown in FIG. 15.

The processing deck 12, for supporting the pipe 90 in position, includes a lower beam 11 with first and second ends 122, 124 and a plurality of pipe rests 126 provided on the lower beam 11.

The overhanging deck 14, for holding and positioning the pipe 90, includes an upper beam 13 and a plurality of hydraulic rams 15 extending down from the upper beam 13.

The pipe stopper 16 is for aligning and stopping the pipe 90 against the force exerted by the mandrel 20 driven by the winch 40.

The lower beam 11 of the processing deck 12 and the upper beam 13 of the overhanging deck 14 are made of a fabricated I beam. The dimension of the I beam is determined by the dimension of the damaged pipe 90. The I beam is approximately thirty five (35) feet long, approximately twelve (12) inches wide, and approximately seven (7) inches high.

The pipe rest 126 of the processing deck 12 is substantially V shaped as shown in FIG. 18.

The hydraulic ram 15 comprises an arm 152 extending from the upper beam 13 and a pinning hand 154 provided at the end of the arm 152. The pinning hand 154 is substantially V-shaped as shown in FIG. 19.

The pipe stopper 16 includes a bevel surface 162 and a stopping surface 164, and the bevel surface 162 and the stopping surface 164 are adapted to align and stop the edge of the pipe 90. The bevel surface 162 and the stopping surface 164 meet each other in approximately from one hundred thirty five (135) to one hundred forty five (145) degrees as shown in FIG. 20 and FIG. 21.

The mandrel 20 includes a tapered head part 21, a barrel part 23, and a mechanical fastener 25.

The tapered head part 21 provided at the first edge 22, and the diameter is smoothly increasing.

The barrel part 23, with a diameter accommodating the inner diameter of the pipe 90, is connected to the tapered head part 21, provided on the side surface 26.

The mechanical fastener 25, for detachably attaching the cable 30, is provided at the end of the tapered head part 21.

The mechanical fastener 25 includes a female screw thread as shown in FIG. 16.

Alternatively, the mechanical fastener 25 includes a hooking device 252, in which case the cable 30 includes a looping device 302 adapted to the hooking device 252 as shown in FIG. 22 and FIG. 23.

The winch 40 includes a hydraulic pump 402. The hydraulic pump 402 is driven by an electrical motor 404. The hydraulic pump 402 may sense the pressure from the load, and the operation of the electrical motor 404 is controlled by the sensed pressure accordingly.

The system 100 for repairing pipe may further include a feeding rack 50, a discharge rack 60, and a slope 70 as shown in FIG. 24.

The feeding rack 50 is for feeding the pipes 90 one by one to the processing deck 12. The discharge rack 60 is for discharging the processed pipes 90 out of the processing deck 12. The slope 70, for returning the mandrel 20, is tilted downward from the finishing end to the starting end as shown in FIG. 25. The mandrel 20 must be detached from the cable 30 and then brought to the finishing end, the far side from the winch 40 after the travel through the pipe 90 in order to be attached to the cable queued through next damaged pipe 90.

The system for repairing pipe may further include a lubricant for reducing the friction and wear between the inner surface of the pipe and the side surface of the barrel part of the mandrel.

The mandrel connected to the end of the wire cable is driven through the damaged pipe for repairing or pushing out the dents. The mandrel travels from the first end the pipe to the second end of the pipe, and must be brought back to the first end of a new pipe to repair. Actually, the mandrel is very heavy. Therefore, the system may further include a tilted slope, provided just by the rack, with a greased rail for sliding the mandrel from the second end to the first end using the universal gravity.

While the invention has been shown and described with reference to different embodiments thereof, it will be appreciated by those skilled in the art that variations in form, detail, compositions and operation may be made without departing from the spirit and scope of the invention as defined by the accompanying claims. 

1. A dedent system for repairing a pipe damaged with dents comprising: a bullet shank comprising a male shank portion and a first latching portion, wherein the first latching portion comprises a first contacting surface and a locking hole provided through the first contacting surface and the male shank portion is configured to be connected with a mandrel, and wherein the locking hole is tilted such that an opening on the first contacting surface is closer to the male shank portion than a portion of the locking hole which is farther from the first contacting surface; and a cable shank comprising a female shank portion and a second latching portion, wherein the second latching portion comprises a second contacting surface and a locking bump provided on the second contacting surface, wherein the locking bump is configured to engage with the locking hole of the bullet shank, wherein the female shank is configured to be connected to a cable, and wherein the locking bump is tilted such that a portion of the locking bump on the first contacting surface is farther to the female shank portion than the a tip portion of the locking bump, wherein the bullet shank and the cable shank are connected by engaging the locking hole and bump so as to be engaged under a force in a first direction parallel to the axis of the cylinders and easily disengaged from each other under a force in a second direction perpendicular to the axis of the cylinders.
 2. The dedent system of claim 1, wherein the male shank portion of the bullet shank has a shape of cylinder, wherein the first latching portion of the bullet shank has a shape of half-cylinder sharing an axis with the male shank portion.
 3. The dedent system of claim 2, wherein the first contacting surface of the latching portion of the bullet shank is substantially flat and parallel to the axis of the cylinders, wherein the locking hole of the bullet shank is substantially perpendicular to the axis of the cylinders, and wherein a cross-section of the locking hole is oblong.
 4. The dedent system of claim 1, wherein the female shank portion of the cable shank has a shape of cylindrical tube, wherein the second latching portion of the cable shank has a shape of half-cylinder sharing an axis with the cable shank portion, and wherein the second contacting surface of the second latching portion of the cable shank is substantially flat and parallel to the axis of the cylinders.
 5. The dedent system of claim 4, wherein the locking bump of the cable shank extends substantially perpendicularly to the axis of the cylinders, wherein the locking bump of the cable shank is configured to lock with the locking hole of the bullet shank, and wherein the first and second contacting surfaces contact each other over most of the first and second contacting surfaces.
 6. The dedent system of claim 1, further comprising: a pipe holding device for holding the pipe having a near end and a far end in position, comprising a processing deck for supporting the pipe in position, an overhanging deck for holding and positioning the pipe, and a pipe stopper for aligning and stopping the pipe against the force exerted by the mandrel driven by the winch; the mandrel, with a cross section and size adapted to be pulled through the interior of the pipe from the far end to the near end, having a first edge, a second edge, and a side surface; the cable having first and second ends, wherein the first end is queued into the pipe and detachably attached to the first edge of the mandrel at the far end of the pipe; a winch disposed at the near end of the pipe and connected to the second end of the cable for winding up the cable; and a slope disposed by the cable and tilted from the far end of the pipe to the near end of the pipe, wherein the mandrel is pulled by the winch with the cable, wherein the mandrel travels through the pipe to push out from inside and remove the dents on the surface of the pipe, and wherein the slope is configured to return the mandrel from the far end to the near end. 